One problem with measuring flows of liquids by means of utility meters in the form of ultrasonic flow meters is that a velocity of the water is measured and translated into a flow rate or accumulated flow volume. Any inaccuracies in such translation may thus result in inaccurate consumption measuring. Because the flow of liquids in a piping system, the design, configuration and geometry of the piping system, and any obstacle encountered by the liquid in flowing in the piping system affects the flow, it may also affect the measured flow velocity. Some effects, which may affect flow measurements, are rotational flow (also known as swirl) and asymmetric flow. Asymmetric flow may e.g. be when the flow in a certain transversal cross-section of the pipe flows with a higher velocity in one half-part of the cross-section compared to the opposite cross-section. If flow variations outside the path of the ultrasound signal used to measure the flow are present, these are not detected and may lead to inaccuracies or imprecisions of the flow measurements.
Such problem may be solved by increasing the complexity of and/or optimizing the design of the path(s) of the ultrasound signal. One downside of this approach may be that it may lead to increased costs of production, or even opens op for other sources of inaccuracies and/or imprecisions, e.g. if the number of reflectors and/or transducers used is increased. Also, it may also lead to an increased number of parts used to assembly the ultrasonic flow meter, which may complicate assembly and also require more productions lines; both of which may lead to both increased production costs and also to higher vulnerability to production errors.
While solving the above problem, the application of ultrasonic flow meters as utility meters (e.g. for billing purposes) would typically require that certain standards are complied with and/or required by typical customers. One example thereof include ultrasonic flow meters having a relatively large measuring range, including a measuring range that also includes relatively low flow rates. Other examples thereof include that the ultrasonic flow meter can measure flows with relatively high accuracy and precision, and that the ultrasonic flow meters can be produced at a competitive cost level and having a relatively long durability. Some of these requirements may be facilitated e.g. by using better electronics and/or transducers, or modifying the configuration of the ultrasound reflector(s) and ultrasonic transducers. This, however, may also increase the complexity of the ultrasonic flow meter and the production cost thereof considerably.